Send as permissions for Exchange

When setting up send as permissions for a user on Exchange recently I had some problems.

Even though I followed the article KB327000 (Link) it wouldn't work.

I kept getting bounce back messages stating a permissions problem.

I then remembered something I read whilst setting up Exmerge permissions that about using groups for permissions.

I setup a new global group and added the user and then the send as works fine.

Strange! I am sure it usually works just with users on the ACE but still maybe this will work for someone else also.

Cheers
Nathan